Notes, summaries, assignments, exams, and problems for Biology

Immunology

By removing serum from pustules of the udder of a cow and injecting it into human skin, an individual suffered from a mild illness but never acquired smallpox. It was the first experiment of active immunization.

1. The Body's Defenses

All organisms have developed mechanisms of defense against the invasion of pathogens. These mechanisms may be nonspecific, preventing entry into the body or destroying them quickly, or very specific, which is known as the immune response.

1.1 Nonspecific Defense Mechanisms

These act against any organism or foreign substance. They are of three types:

a) Natural Barriers: Skin and secretions from the mucosal surfaces.

• Skin is a mechanical barrier because its outermost stratum corneum is fully keratinized.
• It

The Nervous System

The nervous system is a biological system that enables very complex beings to interact with what surrounds us. We can say that it is a huge network responsible for the collection of internal and external stimuli. It processes these stimuli to generate the response that the decision center (brain) considers optimal.

There are two main divisions:

• Central Nervous System: Consists of the brain and spinal cord.
• Peripheral Nervous System: Includes all the nerves of the body that connect internal and external stimuli to the central nervous system.

Peripheral Nervous System

The peripheral nervous system includes different types of nerves:

• Sensory Nerves: Transmit information from sensory receptors (like those for touch, pain, temperature)

The Origin of the Moon

• Sister. The Moon formed while the Earth did, but the Moon is 100 million years younger, and their densities are different.
• Adopted. Both formed, but the Moon formed in an area farthest from the Sun and would have been attracted to the Earth. This does not explain the difference in age.
• Daughter. A planet similar to Mars collided with the Earth. Part of the star that crashed formed a debris cloud that orbited around the Earth. The union of these materials created the Moon.

Prebiotic Synthesis

Hypotheses in which life would have originated on Earth as a result of a process:

• Formation of simple organic molecules. Radiation caused molecules to react, forming simple organic molecules.
• Formation of complex organic molecules.

HIV and AIDS: An Introduction

AIDS (Acquired Immunodeficiency Syndrome) is caused by infection with the retrovirus HIV. This virus attacks and destroys T4 lymphocytes and macrophages. Affected individuals have a depressed immune system, which can lead to certain types of cancers.

Development of the Disease

HIV is found in the blood and other bodily fluids of infected persons. Transmission to a healthy person can occur through various routes. These include contaminated blood transfusions and sexual intercourse between an infected and healthy individual.

Once HIV enters the blood of a new host, it joins T cells and penetrates inside. There, a large number of viruses are created, ultimately destroying the infected cell.

AIDS: Treatment and Prevention

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The First Cells: Cell Evolution

All organisms that currently inhabit the Earth are related because they come from ancestral cells that emerged more than 3,800 million years ago as a result of a slow evolutionary process of organic molecules accumulated in the primeval oceans. It is believed that the decisive moment in the origin of cells was the appearance of a biological membrane.

• The membrane separated the external environment from the internal environment, which favored the existence of a rudimentary metabolism that enabled the ancestral cells to get energy (via nutrition) and use it to reproduce and respond to environmental changes.

Because they originated in a sea of organic molecules, the first cells were probably anaerobic fermentative

Physical Assessment of a Patient with Cancer

Skin

• Inspection: Color, integrity, turgor, humidity, temperature.
• Check for: Injuries (type, size, and location), purpura, petechiae, edema, and appearance of nails.

Head and Neck

• Inspect: Face (asymmetry), eyes, mouth, trachea, maxillary sinuses.
• Palpation: Thyroid.

Thorax

• Inspection: Breathing movements and rate.
• Palpation, percussion, auscultation: Tone, intensity, and duration of breath sounds.

Breasts and Armpits

• Inspection and palpation.

Cardiovascular

• Inspection: Tremors and palpitations in the chest.
• Auscultation, palpation, blood pressure.

Musculoskeletal

• Inspection: Hair distribution, abnormal masses or lesions, asymmetries, nodules.
• Palpation: Painful masses, joint range of motion.

Neurologic

• Presence of

Nutrition: Function and Importance Nutrition includes all processes to get the materials of development and the energy we need to live like .--- La Nutricion: Nutrition is a long process. One step is to take food. Function in the 4 processes involved Nutrition: Circulation - the digestive process, respiration, and excretion Feeding and Nutrients To live, we need the nutrients that food contains. The main groups are carbohydrates, fats, proteins, water, vitamins, and minerals - A diet is complete when it contains all types of nutrients. A balanced diet is when it gives us the necessary amount of each nutrient.

Functions of Muscle Tissue

• Production of body movements
• Stabilization of posture
• Volume regulation of the body
• Movement of chemicals in the body
• Production of heat

Properties of Muscle Tissue

• Electrical excitability
• Contractility
• Extensibility
• Elasticity

Types of Muscle Tissue

There are three types of muscle tissue: striated skeletal, striated cardiac, and smooth.

• Striated skeletal muscle: Called skeletal because the function of these muscles is to move the bones; it often works on a voluntary basis.
• Heart muscle (myocardium): Is located in the heart and is part of its wall. Its movement is involuntary.
• Smooth muscle: Is part of the walls of blood vessels, airways, and some guts. Almost always, this type of muscle movement is involuntary.

Structure of Striated

What is Embryology?

Embryology is the branch of biology that studies the development of an organism from a fertilized egg. It encompasses several key concepts:

• Ontogeny: The transformations that the embryo undergoes during development.
• Phylogeny: The evolutionary history of a species.

Historical Theories of Development

Historically, two main theories attempted to explain embryonic development:

• Preformationism: This theory argued that a miniature version of the organism, called a "homunculus," was present in either the sperm or the egg. Scientists who believed in this were called "animalculists." In 1699, Danlenpatius proposed this theory.
• Epigenesis: This theory proposed that adult body structures were not preformed in the gametes but developed gradually.

Genetics: The Study of Gene Inheritance

Genes are transmitted according to defined rules or laws. Genes are located on chromosomes, which are cellular structures. Sex is determined by specific genes or chromosomes in most living organisms.

Key Genetic Terms

• Genotype: The genetic constitution of an individual, referring to a specific character or the entire set of genes.
• Phenotype: The external expression of the genotype; the observable characteristics of an individual.
• Alleles: Variants that a gene may present. For each gene, an individual has a pair of alleles, often represented by letters.
• Homozygous: An individual having two identical alleles for a specific gene.
• Heterozygous: An individual carrying two different alleles for a specific gene.

Mendelian